JP7431323B2 - Scroll casing and centrifugal compressor - Google Patents

Description

The present disclosure relates to a scroll casing and a centrifugal compressor including the scroll casing.

A centrifugal compressor used in the compressor section of a vehicle or marine turbocharger applies kinetic energy to the fluid through the rotation of an impeller, discharges the fluid radially outward, and uses centrifugal force to increase the pressure of the fluid. This is what you get. Such centrifugal compressors are required to have a high pressure ratio and high efficiency over a wide operating range, and various improvements have been made to these centrifugal compressors.

Typically, a centrifugal compressor includes a scroll casing that rotatably houses an impeller. This scroll casing includes a scroll part that forms a spiral scroll flow path and a diffuser part that forms a diffuser flow path for guiding the fluid that has passed through the impeller to the scroll flow path (for example, Patent Document 1) .

International Publication No. 2018/179112

14 and 15 are explanatory diagrams for explaining the shapes of the diffuser section 04 and the scroll section 05 of the scroll casing 03 of the centrifugal compressor according to the comparative example. As shown in FIGS. 14 and 15, the scroll portion 05 has an inner circumferential surface 051 that defines a scroll passage 050. The inner circumferential surface 051 extends in one direction UD side from the starting end position P01, which is the connection position with the hub side flow path surface 042 of the diffuser flow path 040, and ends at the end position P02, which is the end position on the opposite side from the starting end position P01. It is formed in an arc shape that extends throughout. The scroll casing 03 has a diffuser outlet jaw 054 that includes an inner circumferential surface 051 that includes the end position P02 and a shroud-side flow path surface 041 of the diffuser flow path 040. The fluid that has flowed into the scroll flow path 050 from the outlet of the diffuser flow path 040 has a swirling velocity component, and therefore forms a swirling flow SF that flows toward the UD side in one direction along the inner circumferential surface 051. In such a scroll passage 050, the swirling flow SF flowing along the inner circumferential surface 051 and the exit flow DF of the diffuser passage flowing into the scroll passage 050 from the outlet of the diffuser passage 040 flow into the diffuser outlet jaw. They merge on the downstream side of section 054.

According to the findings of the present inventors, as shown in FIG. If the length T along the direction is large, there is a risk that a low flow velocity area WA called a wake may occur at a position immediately downstream of the diffuser outlet jaw 054 corresponding to the thickness T of the diffuser outlet jaw 054. . If the wake is large, the wake loss of the swirling flow SF increases, which may lead to a decrease in the efficiency of the centrifugal compressor.

In order to suppress wake loss, as shown in FIG. 15, if the thickness T of the diffuser outlet jaw 054 is made small, the difference in the flow angle of the swirling flow SF with respect to the outlet flow DF of the diffuser flow path 040 becomes large. Therefore, due to the interference between the swirling flow SF and the outlet flow DF, at least a portion of the outlet flow DF is blocked. When at least a portion of the outlet flow DF is blocked, the resistance of the fluid passing through the diffuser flow path 040 increases, and there is a possibility that the diffuser stalls. When a diffuser stall is induced, the efficiency of the centrifugal compressor is extremely reduced, and a surge due to the diffuser stall is induced, which may reduce the operating range of the centrifugal compressor. Further, if the thickness T of the diffuser outlet jaw 054 is too small, it is not preferable because there is a risk that the diffuser outlet jaw 054 will be chipped.

In view of the above-mentioned circumstances, an object of at least one embodiment of the present disclosure is to provide a scroll casing and a centrifugal compressor that can suppress a decrease in efficiency and a reduction in the operating range of the centrifugal compressor.

The scroll casing according to the present disclosure is
A scroll casing for a centrifugal compressor,
a diffuser section forming a diffuser flow path of the centrifugal compressor;
a scroll portion forming a scroll flow path of the centrifugal compressor;
The flow path width of the diffuser flow path along the axial direction of the centrifugal compressor is Ta,
a virtual circular arc that touches from a starting end position on the inner circumferential surface of the scroll portion, which is a connection position of the diffuser flow path with the hub-side flow path surface, to a terminal end position, which is an end position on the opposite side of the starting end position on the inner circumferential surface; Define the shortest distance to Tb,
Regarding the angular position around the center of the scroll in the scroll flow path, the confluence position of the start and end of winding of the scroll flow path is set at 60 degrees, and the angle gradually increases from the confluence position toward the downstream side of the scroll flow path. If you define the angular position so that
In the range where the angular position is from 180 degrees to 360 degrees, the relationship Tb/Ta≧1.0 is satisfied.

A centrifugal compressor according to the present disclosure includes the scroll casing.

According to at least one embodiment of the present disclosure, a scroll casing and a centrifugal compressor are provided that can suppress reduction in efficiency and reduction in operating range of the centrifugal compressor.

FIG. 1 is an explanatory diagram for explaining the configuration of a turbocharger including a centrifugal compressor according to an embodiment. 1 is a schematic sectional view schematically showing the compressor side of a turbocharger including a centrifugal compressor according to one embodiment, and is a schematic sectional view including an axis of the centrifugal compressor. It is an explanatory view for explaining the shape of a diffuser part of a scroll casing concerning one embodiment, and a scroll part. It is an explanatory view for explaining the shape of a diffuser part of a scroll casing concerning one embodiment, and a scroll part. It is an explanatory view for explaining the shape of a diffuser part of a scroll casing concerning one embodiment, and a scroll part. It is an explanatory view for explaining the shape of a diffuser part of a scroll casing concerning one embodiment, and a scroll part. FIG. 2 is a schematic diagram of a scroll flow path in an axial view of a centrifugal compressor according to an embodiment. It is an explanatory view for explaining a scroll casing concerning one embodiment, and is an explanatory view showing a relationship between an angular position in a scroll channel and a distance ratio Tb/Ta. It is an explanatory view for explaining the shape of a diffuser part of a scroll casing concerning one embodiment, and a scroll part. It is an explanatory view for explaining a scroll casing concerning one embodiment, and is an explanatory view showing a relationship between an angular position in a scroll passage and a crossing angle α. FIG. 2 is a schematic diagram of a scroll flow path in an axial view of a centrifugal compressor according to an embodiment. FIG. 2 is an explanatory diagram for explaining the shapes of a diffuser portion and a scroll portion at angular positions θ1 and θ2 of a scroll casing according to an embodiment. FIG. 3 is an explanatory diagram for explaining the shapes of the diffuser section and the scroll section at angular positions θ3 and θ4 of the scroll casing according to one embodiment. It is an explanatory view for explaining the shape of a diffuser part of a scroll casing concerning a comparative example, and a scroll part. It is an explanatory view for explaining the shape of a diffuser part of a scroll casing concerning a comparative example, and a scroll part.

Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, and are merely illustrative examples. do not have.
For example, expressions expressing relative or absolute positioning such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""centered,""concentric," or "coaxial" are strictly In addition to representing such an arrangement, it also represents a state in which they are relatively displaced with a tolerance or an angle or distance that allows the same function to be obtained.
For example, expressions such as "same,""equal," and "homogeneous" that indicate that things are in an equal state do not only mean that things are exactly equal, but also have tolerances or differences in the degree to which the same function can be obtained. It also represents the existing state.
For example, expressions expressing shapes such as squares and cylinders do not only refer to shapes such as squares and cylinders in a strict geometric sense, but also include uneven parts and chamfers to the extent that the same effect can be obtained. Shapes including parts, etc. shall also be expressed.
On the other hand, the expressions "comprising,""including," or "having" one component are not exclusive expressions that exclude the presence of other components.
Note that similar configurations may be given the same reference numerals and explanations may be omitted.

(centrifugal compressor, turbocharger)
FIG. 1 is an explanatory diagram for explaining the configuration of a turbocharger including a centrifugal compressor according to one embodiment. FIG. 2 is a schematic sectional view schematically showing the compressor side of a turbocharger including a centrifugal compressor according to one embodiment, and is a schematic sectional view including the axis of the centrifugal compressor.
A centrifugal compressor 1 according to some embodiments of the present disclosure includes an impeller 2 and a scroll casing 3 configured to rotatably accommodate the impeller 2, as shown in FIGS. 1 and 2. . As shown in FIG. 2, the scroll casing 3 includes at least a diffuser part 4 that forms a diffuser passage 40 of the centrifugal compressor 1, and a scroll part 5 that forms a scroll passage 50 of the centrifugal compressor 1. . The diffuser flow path 40 is a flow path for guiding the fluid that has passed through the impeller 2 to a spiral scroll flow path 50 provided around the impeller 2 .

The centrifugal compressor 1 is applicable to, for example, a turbocharger 10 for automobiles, ships, or power generation, other industrial centrifugal compressors, blowers, and the like. In the illustrated embodiment, centrifugal compressor 1 is mounted on turbocharger 10 . The turbocharger 10 includes a centrifugal compressor 1, a turbine 11, and a rotating shaft 12, as shown in FIG. The turbine 11 includes a turbine rotor 13 mechanically connected to the impeller 2 via a rotating shaft 12, and a turbine casing 14 that rotatably accommodates the turbine rotor 13.

In the illustrated embodiment, the turbocharger 10 further includes a bearing 15 rotatably supporting the rotating shaft 12 and a bearing casing 16 configured to house the bearing 15, as shown in FIG. Be prepared. The bearing casing 16 is disposed between the scroll casing 3 and the turbine casing 14, and is mechanically connected to the scroll casing 3 and the turbine casing 14 by a fastening member such as a fastening bolt.

Hereinafter, for example, as shown in FIG. 1, the axis CA of the centrifugal compressor 1, that is, the direction in which the axis of the impeller 2 extends, will be referred to as an axial direction X, and the direction perpendicular to the axis CA will be referred to as a radial direction Y. In the axial direction X, the upstream side in the suction direction of the centrifugal compressor 1, that is, the side where the fluid inlet 31 is located with respect to the impeller 2 (the left side in the figure) is defined as the front side XF. Further, in the axial direction X, the downstream side in the suction direction of the centrifugal compressor 1, that is, the side where the impeller 2 is located with respect to the fluid introduction port 31 (the right side in the figure) is defined as the rear side XR.

In the illustrated embodiment, as shown in FIG. A fluid discharge port 32 is formed for discharging the fluid that has passed through the scroll casing 3 to the outside of the scroll casing 3. The turbine casing 14 is formed with an exhaust gas inlet 141 for introducing exhaust gas into the turbine casing 14 and an exhaust gas outlet 142 for discharging the exhaust gas that has passed through the turbine rotor 13 to the outside of the turbine casing 14. .

The rotating shaft 12 has a longitudinal direction along the axial direction X, as shown in FIG. The impeller 2 is mechanically connected to one longitudinal side (front side XF) of the rotating shaft 12, and the turbine rotor 13 is mechanically connected to the other longitudinal side (rear side XR). . Note that "along a certain direction" in the present disclosure includes not only a certain direction but also a direction inclined with respect to the certain direction.

The turbocharger 10 rotates the turbine rotor 13 using exhaust gas introduced into the turbine casing 14 through the exhaust gas inlet 141 from an exhaust gas generator (for example, an internal combustion engine such as an engine) (not shown). Since the impeller 2 is mechanically connected to the turbine rotor 13 via the rotating shaft 12, it rotates in conjunction with the rotation of the turbine rotor 13. The turbocharger 10 rotates the impeller 2 to compress the fluid introduced into the scroll casing 3 through the fluid inlet 31 and to the fluid supply destination (for example, an engine) through the fluid outlet 32. internal combustion engine).

(impeller)
The impeller 2 includes a hub 21 and a plurality of impeller blades 23 provided on an outer surface 22 of the hub 21, as shown in FIG. Since the hub 21 is mechanically fixed to one side of the rotating shaft 12, the hub 21 and the plurality of impeller blades 23 are provided so as to be rotatable integrally with the rotating shaft 12 around the axis CA of the impeller 2. ing. The impeller 2 is configured to guide fluid introduced from the front side XF in the axial direction X to the outside in the radial direction Y. In the illustrated embodiment, each of the plurality of impeller blades 23 is spaced apart from each other in the circumferential direction around the axis CA. A gap (clearance) is formed between the tips 24 of the plurality of impeller blades 23 and a shroud surface 61 that is curved in a convex manner so as to face the tips 24 .

(scroll casing)
In the illustrated embodiment, the scroll casing 3 includes an intake passage section 7 forming an intake passage 70 for guiding fluid from the outside of the scroll casing 3 to the impeller 2, and a shroud surface, as shown in FIG. 61, and a scroll portion 5 that forms the above-mentioned scroll passage 50 for guiding the fluid that has passed through the impeller 2 to the outside of the scroll casing 3.

The intake flow path 70, the diffuser flow path 40, and the scroll flow path 50 are each formed inside the scroll casing 3. The scroll passage 50 is located outside the impeller 2 in the radial direction. The intake flow path portion 7 has an inner wall surface 71 that forms the intake flow path 70 and extends along the axial direction X. The above-mentioned fluid introduction port 31 is formed at the front XF end of the inner wall surface 71. The scroll portion 5 has an inner circumferential surface 51 that forms a scroll flow path 50.

The diffuser section 4 includes a shroud side flow path surface 41 forming the front side XF portion of the diffuser flow path 40, and a hub side flow path surface 42 provided opposite to the shroud side flow path surface 41 on the rear side XR of the shroud side flow path surface 41. It has a hub-side flow path surface 42 that forms the rear side XR portion of the diffuser flow path 40. In the cross section along the axis CA as shown in FIG. 2, the shroud side flow path surface 41 and the hub side flow path surface 42 each extend along a direction intersecting (orthogonal to in the illustrated example) the axis CA. .

The above-described diffuser section 4 is provided between the shroud section 6 and the scroll section 5. In the illustrated embodiment, the scroll casing 3 is formed with an impeller chamber 60 that accommodates the impeller 2 therein. The shroud surface 61 forms a front side XF portion of the impeller chamber 60. The scroll casing 3 has an impeller chamber forming surface 33 that is located on the rear side XR with respect to the shroud surface 61 and forms the rear side XR portion of the impeller chamber 60 .

The inlet of the diffuser flow path 40 communicates with the impeller chamber 60, and the outlet of the diffuser flow path 40 communicates with the scroll flow path 50. In the illustrated embodiment, the upstream end of shroud side flow path surface 41 smoothly connects to the downstream end of shroud surface 61. The upstream end of the hub side flow path surface 42 is connected to the outer peripheral end of the impeller chamber forming surface 33 via the step surface 34, and the downstream end of the hub side flow path surface 42 is connected smoothly to one end of the inner peripheral surface 51 of the scroll portion 5. is connected to.

The fluid introduced into the scroll casing 3 from the fluid introduction port 31 flows through the intake flow path 70 toward the rear side XR, and then is guided to the impeller 2 (impeller chamber 60). The fluid that has passed through the impeller 2 flows through the diffuser passage 40 and the scroll passage 50 in this order, and then is discharged to the outside of the scroll casing 3 from the fluid discharge port 32.

(distance ratio Tb/Ta)
Each of FIGS. 3 to 6 is an explanatory diagram for explaining the shapes of a diffuser portion and a scroll portion of a scroll casing according to one embodiment. 3 to 6 schematically show a cross section of the centrifugal compressor 1 along the axis CA.
As shown in FIGS. 3 to 6, the flow path width of the diffuser flow path 40 along the axial direction The shortest distance from the starting end position P1, which is the connection position with the road surface 42, to the virtual arc VC that touches the end position P2, which is the end position on the inner circumferential surface 51 on the opposite side to the starting end position P1, is defined as Tb. Note that the shortest distance Tb is positive in the direction from the starting position P1 toward the front side XF, and negative in the direction from the starting position P1 toward the rear side XR.

The starting end position P1 is the rear XR end in the axial direction X on the inner circumferential surface 51, and is a position where the radius of curvature changes from infinite (straight line) to finite. Furthermore, the terminal position P2 is located on the UD side in one direction from the starting position P1. Here, the one direction UD is a counterclockwise direction centered on the center SC of the scroll passage 50 in a cross section along the axis CA of the centrifugal compressor 1 (on the outside of the center SC in the radial direction Y, the direction UD is From the rear side XR to the front side XF in the circumferential direction, and on the inside of the center SC in the radial direction Y, the direction is from the front side XF to the rear side XR in the circumferential direction around the center SC), and the one direction UD side is , on the downstream side.

In the embodiment shown in FIGS. 3 to 6, in the cross section along the axis CA of the centrifugal compressor 1, the inner circumferential surface 51 includes a first circular arc portion 52 extending in one direction UD side from the starting end position P1, The second circular arc portion 53 is formed on the UD side in one direction with respect to the first circular arc portion 52, and includes a second circular arc portion 53 that includes at least the terminal position P2. In FIGS. 3 to 6, the first circular arc portion 52 is shown by a dashed line. The first circular arc portion 52 is formed so that its radius of curvature R1 is constant from the upstream end to the downstream end in one direction UD. Further, the second circular arc portion 53 is formed so that its radius of curvature R2 is constant from the upstream end to the downstream end in one direction UD. The virtual arc VC is in contact with the second arc portion 53 including the end position P2, and its radius of curvature R0 is the same as the radius of curvature R2. The second circular arc portion 53 is formed such that its upstream end smoothly connects to the downstream end of the first circular arc portion 52 at a connection position P3 with the downstream end of the first circular arc portion 52 .
Note that the shape of the inner circumferential surface 51 is not limited to the illustrated embodiment. For example, the inner circumferential surface 51 may be formed such that its curvature continuously decreases toward the UD side in one direction.

As shown in FIGS. 3 to 6, the scroll casing 3 includes a diffuser including a second circular arc portion 53 (inner peripheral surface 51) including the terminal end position P2, and a shroud side flow path surface 41 of the diffuser flow path 40. An exit jaw 54 is formed. In the illustrated embodiment, the diffuser outlet jaw 54 further includes an inner wall surface 55 having a length T along the axial direction. One end of the inner wall surface 55 is connected to the downstream end of the second circular arc portion 53 at the terminal position P2, and the other end is connected to the downstream end 43 of the shroud side flow path surface 41. In the illustrated embodiment, the inner wall surface 55 extends linearly along the axial direction in the cross section along the axis line CA of the centrifugal compressor 1, but the inner wall surface 55 is limited to this shape. Not done. The inner wall surface 55 may be curved in a convex shape outward in the radial direction, for example. In addition, when the width of the diffuser passage 40 is not constant, the passage width Ta of the diffuser passage 40 is set as the outlet of the diffuser passage 40 including the downstream end 43 of the shroud side passage surface 41 (scroll passage 50 The width of the flow path at the communication port 44 may be adopted.

As shown in FIGS. 3 to 6, the fluid that has flowed into the scroll flow path 50 from the outlet of the diffuser flow path 40 has a swirling velocity component, so that it flows in one direction toward the UD side along the inner circumferential surface 51. A flowing swirling flow SF is formed. After flowing along the first circular arc portion 52 and the second circular arc portion 53, such swirling flow SF flows into the scroll passage 50 from the outlet of the diffuser passage 40 on the downstream side of the diffuser outlet jaw 54. It joins the outlet flow DF of the diffuser flow path 40.

The swirling flow SF flows along the virtual arc VC on the downstream side of the diffuser outlet jaw 54. The cross-sectional shape of the scroll casing 3 shown in FIG. 3 satisfies the condition of Tb/Ta=1.0. The cross-sectional shape of the scroll casing 3 shown in FIG. 4 satisfies the condition of Tb/Ta=1.5. As shown in FIGS. 3 and 4, when Tb/Ta≧1.0, the swirling flow SF on the downstream side of the diffuser outlet jaw 54 can have a gentle inclination angle with respect to the outlet flow DF. Interference between the swirling flow SF and the outlet flow DF at the junction with the flow DF can be effectively suppressed. It should be noted that as the value of Tb/Ta becomes larger than 1.0, the thickness T of the diffuser outlet jaw increases, so that a position immediately downstream of the diffuser outlet jaw 54 in the scroll flow path 50 is called a wake. The possibility that a low flow velocity area WA will occur increases. If the wake is large, the wake loss of the swirling flow SF increases, which may lead to a decrease in the efficiency of the centrifugal compressor 1. Therefore, in order to suppress the wake loss of the swirling flow SF, it is preferable not to make the value of Tb/Ta too large than 1.0. The scroll casing 3 preferably satisfies the relationship Tb/Ta≦1.75, and more preferably satisfies the relationship Tb/Ta≦1.60.

The cross-sectional shape of the scroll casing 3 shown in FIG. 5 satisfies the condition of Tb/Ta=0.5. The cross-sectional shape of the scroll casing 3 shown in FIG. 6 satisfies the condition of Tb/Ta<0. As shown in FIGS. 5 and 6, as the value of Tb/Ta becomes smaller than 1.0, the swirling flow SF on the downstream side of the diffuser outlet jaw 54 and the diffuser flow path flowing into the scroll flow path 50 The degree of interference with the outlet flow DF of the diffuser flow path 40 increases, and the degree of blockage of the outlet flow DF of the diffuser flow path 40 increases. In FIG. 5, the shroud side (front side XF) of the outlet flow DF is blocked by the swirling flow SF on the downstream side of the diffuser outlet jaw 54, whereas in FIG. The outlet flow DF is blocked from the shroud side to the hub side (rear side XR) by the swirling flow SF. If at least the shroud side of the outlet flow DF is blocked, the resistance of the fluid passing through the diffuser flow path 40 increases, and there is a possibility that diffuser stall may be induced. When the diffuser stall is induced, the efficiency of the centrifugal compressor 1 is extremely reduced, and a surge due to the diffuser stall is induced, which may reduce the operating range of the centrifugal compressor 1. Further, as the value of Tb/Ta decreases, the thickness T of the diffuser outlet jaw 54 decreases, but if the thickness T is too small, there is a risk that the diffuser outlet jaw 54 will chip, which is not preferable. Note that the adverse effect on the efficiency of the centrifugal compressor 1 due to wake loss of the swirling flow SF is smaller than the adverse effect on the efficiency of the centrifugal compressor 1 due to blockage of the outlet flow DF. For this reason, it is preferable that the value of Tb/Ta be larger than 1.0 than smaller than 1.0.

FIG. 7 is a schematic diagram of a scroll flow path in an axial view of a centrifugal compressor according to an embodiment. As shown in FIG. 7, regarding the angular position θ around the scroll center O in the scroll passage 50 described above, the confluence position P of the winding start 501 and the winding end 502 of the scroll passage 50 is 60 degrees, and from the confluence position P The angular position θ is defined so that the angle gradually increases toward the downstream side of the scroll flow path 50 (in the clockwise direction around the scroll center O in the figure). Further, the range where the angular position θ ranges from 60 degrees to 180 degrees is defined as the upstream range RU, and the range where the angular position θ ranges from 180 degrees to 360 degrees is defined as the downstream range RD. Further, as shown in FIG. 7, the scroll flow path 50 is compared to the cross section when the scroll flow path 50 is cut by a plane including the axis CA of the centrifugal compressor 1 at the circumferential position where the angular position is θ. Let A be the cross-sectional area, and let R be the distance from the scroll center O to the center SC in the cross section of the scroll channel 50. The scroll passage 50 is formed such that the A/R increases as the angular position θ increases. In one embodiment, the scroll passage 50 is formed such that the value of A/R increases at a constant slope in at least one of the upstream range RU and the downstream range RD.

FIG. 8 is an explanatory diagram for explaining the scroll casing according to one embodiment, and is an explanatory diagram showing the relationship between the angular position in the scroll passage and the distance ratio Tb/Ta. In FIG. 8, the above-mentioned angular position θ is plotted on the horizontal axis, and the above-mentioned distance ratio Tb/Ta is plotted on the vertical axis. In the embodiment shown in FIG. 8, Tb/Ta of the scroll casing 3 increases as the angular position θ increases, corresponding to the increase in A/R.
As shown in FIG. 8, the scroll casing 3 according to some embodiments has Tb/Ta≧1.0 in the range where the angular position θ is from 180 degrees to 360 degrees, that is, in the downstream range RD. Satisfy the relationship.

If the value of Tb/Ta is too small (if the relationship Tb/Ta<1.0 is satisfied), the outlet flow DF of the diffuser flow path 40 and the swirling flow SF in the scroll flow path 50 will interfere, This increases the resistance of the fluid passing through the diffuser flow path 40, and there is a possibility that the diffuser stalls. When the diffuser stall is induced, the efficiency of the centrifugal compressor 1 is extremely reduced, and a surge due to the diffuser stall is induced, which may reduce the operating range of the centrifugal compressor 1. In order to avoid this, it is preferable to satisfy the relationship Tb/Ta≧1.0. According to the above configuration, the scroll casing 3 satisfies the relationship Tb/Ta≧1.0 in the range where the angular position θ is from 180 degrees to 360 degrees (downstream range RD), so the above downstream range RD In this case, interference between the outlet flow DF of the diffuser flow path 40 and the swirling flow SF within the scroll flow path 50 can be suppressed. As a result, clogging of the diffuser flow path 40 can be suppressed, so that a decrease in efficiency of the centrifugal compressor 1 and a reduction in the operating range can be suppressed.

In some embodiments, the scroll casing 3 described above has Tb/Ta≧0 in the range where the angular position θ is from 60 degrees to 180 degrees, that is, in the upstream range RU, as shown in FIG. Satisfies relationship 5.

In order to suppress interference between the outlet flow DF of the diffuser flow path 40 and the swirling flow SF in the scroll flow path 50, the angular position θ of the scroll casing 3 must be in a range from 60 degrees to 180 degrees (upstream range RU). Also, it is preferable that Tb/Ta≧1.0. However, since the cross-sectional area A of the scroll flow path 50 becomes smaller toward the winding start 501 side of the scroll flow path 50, it becomes difficult to satisfy the relationship Tb/Ta≧1.0 in the upstream range RU. There is. According to the above configuration, the relationship Tb/Ta≧0.5 is satisfied in the range where the angular position θ is from 60 degrees to 180 degrees (upstream range RU). In this case, it is possible to suppress interference between the outlet flow DF of the diffuser flow path 40 and the swirling flow SF within the scroll flow path 50 in the upstream range RU. As a result, clogging of the diffuser flow path 40 can be suppressed, so that a decrease in efficiency of the centrifugal compressor 1 and a reduction in the operating range can be suppressed. In some embodiments, the scroll casing 3 described above may be formed so as to satisfy the relationship Tb/Ta≧1.0 in the upstream range RU and the downstream range RD. In this case, interference between the outlet flow DF and the swirling flow SF can be effectively suppressed.

In some embodiments, the scroll casing 3 described above, as shown in FIG. 8, satisfies Tb/Ta≦1. 75 relationships are satisfied.

If the value of Tb/Ta is too large (if the relationship Tb/Ta>1.75 is satisfied), the above-mentioned area WA will expand as the thickness T of the diffuser outlet jaw 54 increases. Since the wake loss increases, there is a possibility that the efficiency of the centrifugal compressor 1 will decrease. According to the above configuration, the relationship Tb/Ta≦1.75 is satisfied in the range where the angular position θ is from 180 degrees to 360 degrees (downstream range RD). In this case, in the downstream range RD, a decrease in efficiency of the centrifugal compressor 1 due to wake loss can be suppressed. In some embodiments, the scroll casing 3 described above satisfies the relationship Tb/Ta≦1.75 in the upstream range RU and the downstream range RD. In this case, a decrease in efficiency of the centrifugal compressor 1 due to wake loss can be suppressed in the upstream range RU and the downstream range RD.

(intersection angle α)
FIG. 9 is an explanatory diagram for explaining the shapes of the diffuser section and the scroll section of the scroll casing according to one embodiment. As shown in FIG. 9, the intersection angle between a virtual tangent VT that is in contact with the terminal end position P2 on the inner circumferential surface 51 of the scroll portion 5 and the radial direction Y of the centrifugal compressor 1 is defined as α. Note that two crossing angles are generated by the virtual tangent VT and the radial direction Y, and the smaller of the two crossing angles is set as the crossing angle α.

In some of the embodiments described above, the distance ratio Tb/Ta is used as a parameter value related to the shape of the scroll casing 3, but in some other embodiments, the intersection angle α may be used as the parameter value. As the crossing angle α increases, the inclination angle of the swirling flow SF on the downstream side of the diffuser outlet jaw 54 with respect to the exit flow DF increases correspondingly to the crossing angle α. As the inclination angle increases, the degree of interference between the swirling flow SF and the outlet flow DF of the diffuser flow path 40 increases, and the degree of obstruction of the outlet flow DF of the diffuser flow path 40 increases. Therefore, in order to suppress blockage of the outlet flow DF, it is preferable to make the crossing angle α small. The scroll casing 3 preferably satisfies the relationship of crossing angle α≦70°, and more preferably satisfies the relationship of crossing angle α≦50°.

FIG. 10 is an explanatory diagram for explaining the scroll casing according to one embodiment, and is an explanatory diagram showing the relationship between the angular position in the scroll passage and the crossing angle α. In FIG. 10, the above-mentioned angular position θ is plotted on the horizontal axis, and the above-mentioned intersection angle α is plotted on the vertical axis. Note that in the embodiment shown in FIG. 10, the crossing angle α of the scroll casing 3 becomes smaller as the angular position θ becomes larger.
As shown in FIG. 10, the scroll casing 3 according to some embodiments satisfies the relationship α≦50° in the range where the angular position θ is from 180 degrees to 360 degrees, that is, in the downstream range RD. .

If the intersection angle α is too large, the outlet flow DF of the diffuser flow path 40 and the swirling flow SF in the scroll flow path 50 will interfere, and this will increase the resistance of the fluid passing through the diffuser flow path 40. , there is a risk that diffuser stall may be induced. When the diffuser stall is induced, the efficiency of the centrifugal compressor 1 is extremely reduced, and a surge due to the diffuser stall is induced, which may reduce the operating range of the centrifugal compressor 1. In order to avoid this, it is preferable to satisfy the relationship α≦50°. According to the above configuration, the scroll casing 3 satisfies the relationship α≦50° in the range where the angular position θ is from 180 degrees to 360 degrees (downstream range RD), so that the diffuser flow is reduced in the downstream range RD. Interference between the outlet flow DF of the passage 40 and the swirling flow SF within the scroll passage 40 can be suppressed. As a result, clogging of the diffuser flow path 40 can be suppressed, so that a decrease in efficiency of the centrifugal compressor 1 and a reduction in the operating range can be suppressed. Note that this embodiment can be implemented independently.

In some embodiments, as shown in FIG. 10, the scroll casing 3 described above has a relationship of α≦70° in the range where the angular position θ is from 60 degrees to 180 degrees, that is, in the upstream range RU. satisfy.

In order to suppress interference between the outlet flow DF of the diffuser flow path 40 and the swirling flow SF in the scroll flow path 50, the angular position θ of the scroll casing 3 must be in a range from 60 degrees to 180 degrees (upstream range RU). Also, it is preferable to satisfy the relationship α≦50°. However, since the cross-sectional area A of the scroll flow path 50 becomes smaller toward the winding start 501 side of the scroll flow path 50, it may be difficult to satisfy the relationship α≦50° in the upstream range RU. According to the above configuration, the relationship α≦70° is satisfied in the range where the angular position θ is from 60 degrees to 180 degrees (upstream range RU). In this case, it is possible to suppress interference between the outlet flow DF of the diffuser flow path 40 and the swirling flow SF within the scroll flow path 50 in the upstream range RU. As a result, clogging of the diffuser flow path 40 can be suppressed, so that a decrease in efficiency of the centrifugal compressor 1 and a reduction in the operating range can be suppressed. In some embodiments, the scroll casing 3 described above may be formed so as to satisfy the relationship α≦50° in the upstream range RU and the downstream range RD. In this case, interference between the outlet flow DF and the swirling flow SF can be effectively suppressed.

In some embodiments described above, either the distance ratio Tb/Ta or the crossing angle α is used as a parameter value regarding the shape of the scroll casing 3, but in some other embodiments, the distance ratio Tb/Ta and Both of the intersection angles α may be set as the above parameter values.
In some embodiments, the scroll casing 3 described above has Tb/Ta≧1.0 and α≦50° in the range where the angular position θ is from 180 degrees to 360 degrees, that is, in the downstream range RD. Satisfy the relationship.

According to the above configuration, the scroll casing 3 satisfies not only the relationship of Tb/Ta≧1.0 but also the relationship of α≦50° in the range where the angular position θ is from 180 degrees to 360 degrees (downstream range RD). Since the relationship is satisfied, the outlet flow DF of the diffuser flow path 40 and the swirling flow SF in the scroll flow path 50 interfere with each other in the downstream range RD compared to the case where only the relationship Tb/Ta≧1.0 is satisfied. can be suppressed more effectively. Thereby, blockage of the diffuser flow path 40 can be effectively suppressed, so that a decrease in the efficiency of the centrifugal compressor 1 and a reduction in the operating range can be effectively suppressed.

In some embodiments, the scroll casing 3 described above has Tb/Ta≧0.5 and α≦70° in the range where the angular position θ is from 60 degrees to 180 degrees, that is, in the upstream range RU. Satisfy the relationship.

According to the above configuration, the scroll casing 3 satisfies not only the relationship of Tb/Ta≧0.5 but also the relationship of α≦70° in the range where the angular position θ is from 60 degrees to 180 degrees (upstream range RU). Since the relationship is satisfied, the outlet flow DF of the diffuser flow path 40 and the swirling flow SF in the scroll flow path 50 interfere with each other in the upstream range RU compared to the case where only the relationship Tb/Ta≧0.5 is satisfied. can be suppressed more effectively. Thereby, blockage of the diffuser flow path 40 can be effectively suppressed, so that a decrease in the efficiency of the centrifugal compressor 1 and a reduction in the operating range can be effectively suppressed.

(Shape change in the circumferential direction of the scroll flow path)
FIG. 11 is a schematic diagram of a scroll flow path in an axial view of a centrifugal compressor according to an embodiment. As shown in FIG. 11, the above-mentioned angular position θ includes angular position θ1 and angular position θ2, which is larger than angular position θ1. FIG. 12 is an explanatory diagram for explaining the shapes of the diffuser part and the scroll part at angular positions θ1 and θ2 of the scroll casing according to one embodiment. In FIG. 12, the scroll casing 3 is schematically shown in angular positions θ1 and θ2. In FIG. 12, the inner circumferential surface 51 and inner wall surface 55 of the scroll portion 5 at the angular position θ1 are shown by a solid line, and the inner circumferential surface 51 and the inner wall surface 55 of the scroll portion 5 at the angular position θ2 are shown by a two-dot chain line.

In some embodiments, as shown in FIG. 12, the scroll casing 3 described above is arranged so that the end position P2 and the downstream end 43 of the shroud side flow path surface 41 of the diffuser flow path 40 are at the angular position θ1. The length along the axial direction of the centrifugal compressor is T1, and the length along the axial direction between the terminal position P2 and the downstream end 43 of the shroud side flow path surface 41 at the position θ2 where the angular position θ is larger than θ1 is defined as T2, the relationship T1<T2 is satisfied. In the illustrated embodiment, the scroll flow path 50 is formed such that the above-mentioned length T increases continuously or stepwise from the winding start 501 side to the winding end 502 side.

Usually, the length T along the axial direction of the centrifugal compressor 1 between the end position P2 and the downstream end 43 of the shroud side flow path surface 41 of the diffuser flow path 40 is set uniformly in the circumferential direction of the centrifugal compressor 1. However, in this case, if Tb/Ta and intersection angle α are made into a shape that satisfies the above-mentioned relationship for each angular position θ, the shape at the winding end 502 side of the scroll flow path 50 will be inappropriate, and the centrifugal This may lead to a decrease in the efficiency of the compressor 1. According to the above configuration, the length T2 at the angular position θ2 of the scroll casing 3 is larger than the length T1 at the angular position θ1. The scroll flow path 50 can be shaped appropriately for each angular position θ while maintaining the relationship. Thereby, a decrease in efficiency of the centrifugal compressor 1 can be suppressed.

As shown in FIG. 11, the above-mentioned angular position θ includes angular position θ3 and angular position θ4, which is larger than angular position θ3. FIG. 13 is an explanatory diagram for explaining the shapes of the diffuser section and the scroll section at angular positions θ3 and θ4 of the scroll casing according to one embodiment. In FIG. 13, the scroll casing 3 is schematically shown at angular positions θ3 and θ4. In FIG. 13, the inner circumferential surface 51, inner wall surface 55, and shroud side flow path surface 41 of the scroll portion 5 at the angular position θ3 are indicated by dashed lines, and the inner circumferential surface 51, the inner wall surface 55, and the shroud side flow path surface 41 of the scroll portion 5 at the angular position θ4 are indicated by dashed lines. The side flow path surface 41 is shown by a solid line.

In some embodiments, the scroll casing 3 described above is arranged so that the shroud-side flow path surface 41 of the diffuser flow path 40 extends from the axis CA of the centrifugal compressor 1 at the angular position θ of θ3, as shown in FIG. The length along the radial direction of the centrifugal compressor 1 to the downstream end 43 is d1, and the radial direction from the axis CA to the downstream end 43 of the shroud side flow path surface 41 at the position θ4 where the angular position θ is larger than θ3. When the length along the line is defined as d2, the relationship d1>d2 is satisfied. In the illustrated embodiment, the diffuser flow path 40 extends from the axis CA of the centrifugal compressor 1 to the downstream end 43 of the shroud side flow path surface 41 of the diffuser flow path 40 as it goes from the winding start 501 side to the winding end 502 side. The length d along the radial direction of the centrifugal compressor 1 increases continuously or stepwise.

Usually, the length d along the radial direction of the centrifugal compressor 1 from the axis CA of the centrifugal compressor 1 to the downstream end 43 of the shroud side flow path surface 41 of the diffuser flow path 40 is uniform in the circumferential direction of the centrifugal compressor 1. However, in this case, if Tb/Ta and the intersection angle α are set to a shape that satisfies the above-mentioned relationship for each angular position θ, the shape of the scroll passage 50 at the winding end side will be inappropriate. This may lead to a decrease in the efficiency of the centrifugal compressor 1. According to the above configuration, since the length d2 at the angular position θ4 is larger than the length d1 at the angular position θ3, the scroll casing 3 has the above-mentioned Tb/Ta and crossing angle α for each angular position θ. The scroll flow path 50 can be shaped appropriately for each angular position θ while maintaining the relationship. Thereby, a decrease in efficiency of the centrifugal compressor 1 can be suppressed.

Note that in the embodiment shown in FIG. 13, the above-mentioned length T is the same at angular positions θ3 and θ4, but similarly to the several embodiments described above, the length T at angular position θ4 is It may be made larger than the length T at position θ3.

The centrifugal compressor 1 according to some embodiments includes the scroll casing 3 described above. In this case, the scroll casing 3 can suppress interference between the outlet flow DF of the diffuser flow path 40 and the swirling flow SF within the scroll flow path 50. As a result, clogging of the diffuser flow path 40 can be suppressed, so that a decrease in efficiency of the centrifugal compressor 1 and a reduction in the operating range can be suppressed.

The present disclosure is not limited to the embodiments described above, and also includes forms in which modifications are added to the embodiments described above, and forms in which these forms are appropriately combined.

The contents described in the several embodiments described above can be understood, for example, as follows.

1) The scroll casing (3) according to at least one embodiment of the present disclosure includes:
A scroll casing (3) of a centrifugal compressor (1),
a diffuser part (4) forming a diffuser flow path (40) of the centrifugal compressor (1);
a scroll part (5) forming a scroll flow path (50) of the centrifugal compressor (1),
The flow path width of the diffuser flow path (40) along the axial direction of the centrifugal compressor (1) is Ta,
From the starting end position (P1), which is the connection position of the diffuser flow path (40) with the hub side flow path surface (42) on the inner peripheral surface (51) of the scroll portion (5), to the inner peripheral surface (51) of the scroll portion (5). Define the shortest distance to a virtual arc (VC) that touches the end position (P2), which is the end position opposite to the start end position (P1), as Tb,
Regarding the angular position (θ) around the scroll center (O) in the scroll flow path (50), the confluence position (P) of the winding start (501) and winding end (502) of the scroll flow path (50) is set at 60 degrees. If the angular position (θ) is defined so that the angle gradually increases from the merging position (P) toward the downstream side of the scroll flow path (50),
In the range where the angular position (θ) ranges from 180 degrees to 360 degrees (downstream range RD), the relationship Tb/Ta≧1.0 is satisfied.

If the value of Tb/Ta is too small (if the relationship Tb/Ta<1.0 is satisfied), the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) in the scroll flow path will interfere. However, this increases the resistance of the fluid passing through the diffuser flow path (40), and there is a possibility that the diffuser stalls. When the diffuser stall is induced, the efficiency of the centrifugal compressor (1) is extremely reduced, and a surge due to the diffuser stall is induced, which may reduce the operating range of the centrifugal compressor (1). In order to avoid this, it is preferable to satisfy the relationship Tb/Ta≧1.0. According to the above configuration 1), the scroll casing (3) satisfies the relationship Tb/Ta≧1.0 in the range of the angular position (θ) from 180 degrees to 360 degrees (downstream range RD). In the downstream range, interference between the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) in the scroll flow path can be suppressed. As a result, blockage of the diffuser flow path (40) can be suppressed, so that a decrease in efficiency and a reduction in the operating range of the centrifugal compressor (1) can be suppressed.

2) In some embodiments, the scroll casing (3) described in 1) above,
In the range where the angular position (θ) ranges from 60 degrees to 180 degrees (upstream range RU), the relationship Tb/Ta≧0.5 is satisfied.

According to configuration 2) above, the relationship Tb/Ta≧0.5 is satisfied in the range where the angular position (θ) ranges from 60 degrees to 180 degrees (upstream range RU). In this case, interference between the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) in the scroll flow path can be suppressed in the upstream range (RU). As a result, blockage of the diffuser flow path (40) can be suppressed, so that a decrease in efficiency and a reduction in the operating range of the centrifugal compressor (1) can be suppressed.

3) In some embodiments, the scroll casing (3) described in 1) or 2) above,
In the range where the angular position (θ) extends from 180 degrees to 360 degrees (downstream range RD), the relationship Tb/Ta≦1.75 is satisfied.

If the value of Tb/Ta is too large (if the relationship Tb/Ta>1.75 is satisfied), the wake loss will increase as the thickness (T) of the diffuser outlet jaw (54) increases. Therefore, there is a possibility that the efficiency of the centrifugal compressor (1) will decrease. According to configuration 3) above, the relationship Tb/Ta≦1.75 is satisfied in the range where the angular position (θ) extends from 180 degrees to 360 degrees (downstream range RD). In this case, in the downstream range (RD), reduction in efficiency of the centrifugal compressor (1) due to wake loss can be suppressed.

4) In some embodiments, the scroll casing (3) according to any one of 1) to 3) above,
α is the intersection angle between a virtual tangent (VT) in contact with the terminal position (P2) on the inner circumferential surface (51) of the scroll portion (5) and the radial direction (Y) of the centrifugal compressor (1). If defined,
In a range where the angular position (θ) ranges from 180 degrees to 360 degrees (downstream range RD), the relationship α≦50° is satisfied.

According to configuration 4) above, the scroll casing (3) has not only the relationship of Tb/Ta≧1.0 in the range (downstream range RD) of the angular position (θ) from 180 degrees to 360 degrees. , α≦50°, so compared to the case where only the relationship Tb/Ta≧1.0 is satisfied, in the downstream range (RD), the outlet flow (DF) of the diffuser flow path and the inside of the scroll flow path are Interference with the swirling flow (SF) can be more effectively suppressed. Thereby, blockage of the diffuser flow path (40) can be effectively suppressed, so that a decrease in efficiency and a reduction in the operating range of the centrifugal compressor (1) can be effectively suppressed.

5) In some embodiments, the scroll casing (3) described in 4) above,
In the range where the angular position (θ) ranges from 60 degrees to 180 degrees (upstream range RU), the relationship α≦70° is satisfied.

According to configuration 5) above, the relationship α≦70° is satisfied in the range where the angular position (θ) ranges from 60 degrees to 180 degrees (upstream range RU). In this case, interference between the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) in the scroll flow path can be suppressed in the upstream range (RU). As a result, blockage of the diffuser flow path (40) can be suppressed, so that a decrease in efficiency and a reduction in the operating range of the centrifugal compressor (1) can be suppressed.

6) The scroll casing (3) according to at least one embodiment of the present disclosure includes:
A scroll casing (3) of a centrifugal compressor (1),
a diffuser part (4) forming a diffuser flow path (40) of the centrifugal compressor (1);
a scroll part (5) forming a scroll flow path (50) of the centrifugal compressor (1),
a terminal end that is an end position on the inner circumferential surface (51) of the scroll portion (5) on the opposite side from a starting end position (P1) that is a connection position with the hub-side flow path surface (42) of the diffuser flow path (40); The intersection angle between the virtual tangent (VT) touching the position (P2) and the radial direction (Y) of the centrifugal compressor (1) is defined as α,
Regarding the angular position (θ) around the scroll center (O) in the scroll flow path (50), the confluence position (P) of the winding start (501) and winding end (502) of the scroll flow path (50) is set at 60 degrees. If the angular position (θ) is defined so that the angle gradually increases from the merging position (P) toward the downstream side of the scroll flow path (50),
In a range where the angular position (θ) ranges from 180 degrees to 360 degrees (downstream range RD), the relationship α≦50° is satisfied.

If the crossing angle α is too large, the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) in the scroll flow path will interfere, and this will cause the flow of fluid passing through the diffuser flow path (40) to There is a risk that resistance will increase and diffuser stall will be induced. When the diffuser stall is induced, the efficiency of the centrifugal compressor (1) is extremely reduced, and a surge due to the diffuser stall is induced, which may reduce the operating range of the centrifugal compressor (1). According to configuration 6) above, the scroll casing (3) satisfies the relationship α≦50° in the range where the angular position (θ) extends from 180 degrees to 360 degrees (downstream range RD), so the scroll casing (3) In the range (RD), interference between the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) in the scroll flow path can be suppressed. As a result, blockage of the diffuser flow path (40) can be suppressed, so that a decrease in efficiency and a reduction in the operating range of the centrifugal compressor (1) can be suppressed.

7) In some embodiments, the scroll casing (3) described in 6) above,
In the range where the angular position (θ) ranges from 60 degrees to 180 degrees (upstream range RU), the relationship α≦70° is satisfied.

According to configuration 7) above, the relationship α≦70° is satisfied in the range where the angular position (θ) ranges from 60 degrees to 180 degrees (upstream range RU). In this case, interference between the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) in the scroll flow path can be suppressed in the upstream range (RU). As a result, blockage of the diffuser flow path (40) can be suppressed, so that a decrease in efficiency and a reduction in the operating range of the centrifugal compressor (1) can be suppressed.

8) In some embodiments, the scroll casing (3) according to any one of 1) to 7) above,
of the centrifugal compressor (1) between the terminal position (P2) and the downstream end (43) of the shroud side flow path surface (41) of the diffuser flow path (40) at the angular position (θ) of θ1; The length along the axial direction is T1,
The length along the axial direction between the terminal position (P2) and the downstream end (43) of the shroud side flow path surface (41) at the position θ2 where the angular position (θ) is larger than θ1 is T2. , when defined as
The relationship T1<T2 is satisfied.

Usually, the length (T) along the axial direction of the centrifugal compressor (1) between the terminal position (P2) and the downstream end (43) of the shroud side flow path surface (41) of the diffuser flow path (40) is The scroll flow path ( 50) at the winding end (502) side becomes inappropriate, which may lead to a decrease in efficiency of the centrifugal compressor (1). According to configuration 8) above, since the length T2 at the angular position θ2 is larger than the length T1 at the angular position θ1, the scroll casing (3) has Tb/Ta at each angular position (θ). The scroll flow path (50) can be shaped appropriately for each angular position (θ) while maintaining the above-mentioned relationship for the intersection angle α. Thereby, a decrease in efficiency of the centrifugal compressor (1) can be suppressed.

9) In some embodiments, the scroll casing (3) according to any one of 1) to 8) above,
The centrifugal flow from the axis (CA) of the centrifugal compressor (1) to the downstream end (43) of the shroud side flow path surface (41) of the diffuser flow path (40) at the angular position (θ) of θ3. The length of the compressor (1) along the radial direction (Y) is d1,
The length along the radial direction (Y) from the axis (CA) to the downstream end (43) of the shroud side flow path surface (41) at a position θ4 where the angular position (θ) is larger than θ3. When defined as d2,
The relationship d1>d2 is satisfied.

Usually, along the radial direction (Y) of the centrifugal compressor (1) from the axis (CA) of the centrifugal compressor (1) to the downstream end (43) of the shroud side flow path surface (41) of the diffuser flow path (40). The length (d) of the centrifugal compressor (1) is set uniformly in the circumferential direction of the centrifugal compressor (1). If the shape is filled, the shape of the scroll flow path (50) at the winding end (502) side will be inappropriate, which may lead to a decrease in the efficiency of the centrifugal compressor (1). According to configuration 9) above, since the length d2 at the angular position θ4 is larger than the length d1 at the angular position θ3, the scroll casing (3) has Tb/Ta at each angular position (θ). The scroll flow path (50) can be shaped appropriately for each angular position (θ) while maintaining the above-mentioned relationship for the intersection angle α. Thereby, a decrease in efficiency of the centrifugal compressor (1) can be suppressed.

10) A centrifugal compressor (1) according to at least one embodiment of the present disclosure,
The scroll casing (3) according to any one of 1) to 9) above is provided.

According to configuration 10), the scroll casing (3) can suppress interference between the outlet flow (DF) of the diffuser flow path and the swirling flow (SF) within the scroll flow path. As a result, blockage of the diffuser flow path (40) can be suppressed, so that a decrease in efficiency and a reduction in the operating range of the centrifugal compressor (1) can be suppressed.

1 Centrifugal compressor 2 Impeller 21 Hub 22 Outer surface 23 Impeller blade 24 Tip 3,03 Scroll casing 31 Fluid inlet 32 Fluid outlet 33 Impeller chamber forming surface 34 Step surface 4,04 Diffuser section 40,040 Diffuser channel 41,041 Shroud side flow path surface 42,042 Hub side flow path surface 43,043 Downstream end 5,05 Scroll portion 50,050 Scroll flow path 51,051 Inner peripheral surface 52 First circular arc portion 53 Second circular arc portion 54,054 Diffuser outlet jaw portion 55 Inner wall surface 6 Shroud section 60 Impeller chamber 61 Shroud surface 7 Intake flow path section 70 Intake flow path 71 Inner wall surface 10 Turbocharger 11 Turbine 12 Rotating shaft 13 Turbine rotor 14 Turbine casing 141 Exhaust gas inlet 142 Exhaust gas outlet 15 Bearing 16 Bearing Casing A Cross-sectional area CA Axis DF Outlet flow O Scroll center P Merging position P1, P01 Starting position P2, P02 Terminating position P3 Connection position R0, R1, R2 Radius of curvature RD Downstream range RU Upstream range SF Swirling flow Ta Diffuser flow path Channel width Tb Shortest distance UD Unidirectional VC Virtual arc VT Virtual tangent WA Area X Axial direction XF Front side XR Back side Y Radial direction

Claims (9)

A scroll casing for a centrifugal compressor,
a diffuser section forming a diffuser flow path of the centrifugal compressor;
a scroll portion forming a scroll flow path of the centrifugal compressor;
The flow path width of the diffuser flow path along the axial direction of the centrifugal compressor is Ta,
a virtual circular arc that touches from a starting end position on the inner circumferential surface of the scroll portion, which is a connection position of the diffuser flow path with the hub-side flow path surface, to a terminal end position, which is an end position on the opposite side of the starting end position on the inner circumferential surface; Define the shortest distance to Tb,
Regarding the angular position around the center of the scroll in the scroll flow path, the confluence position of the start and end of winding of the scroll flow path is set at 60 degrees, and the angle gradually increases from the confluence position toward the downstream side of the scroll flow path. If you define the angular position so that
In the range where the angular position ranges from 180 degrees to 360 degrees, the relationship Tb/Ta≧1.0 is satisfied,
The length along the radial direction of the centrifugal compressor from the axis of the centrifugal compressor to the downstream end of the shroud side flow path surface of the diffuser flow path at the angular position θ3 is d1,
When the length along the radial direction from the axis to the downstream end of the shroud side flow path surface at the position θ4 where the angular position is larger than θ3 is defined as d2,
satisfies the relationship d1>d2,
scroll casing. In the range where the angular position ranges from 60 degrees to 180 degrees, the relationship Tb/Ta≧0.5 is satisfied;
Scroll casing according to claim 1. In the range where the angular position ranges from 180 degrees to 360 degrees, the relationship Tb/Ta≦1.75 is satisfied;
Scroll casing according to claim 1 or 2. When the intersection angle between a virtual tangent in contact with the terminal position on the inner circumferential surface of the scroll portion and the radial direction of the centrifugal compressor is defined as α,
In the range where the angular position ranges from 180 degrees to 360 degrees, the relationship α≦50° is satisfied;
Scroll casing according to any one of claims 1 to 3. In the range where the angular position ranges from 60 degrees to 180 degrees, the relationship α≦70° is satisfied;
Scroll casing according to claim 4. A scroll casing for a centrifugal compressor,
a diffuser section forming a diffuser flow path of the centrifugal compressor;
a scroll portion forming a scroll flow path of the centrifugal compressor;
An imaginary tangent on the inner circumferential surface of the scroll portion that touches a terminal end position that is an end position opposite to a starting end position that is a connection position of the diffuser flow path with the hub-side flow path surface, and a radial direction of the centrifugal compressor. Define the intersection angle as α,
Regarding the angular position around the center of the scroll in the scroll flow path, the confluence position of the start and end of winding of the scroll flow path is set at 60 degrees, and the angle gradually increases from the confluence position toward the downstream side of the scroll flow path. If you define the angular position so that
In the range where the angular position ranges from 180 degrees to 360 degrees, the relationship α≦50° is satisfied;
scroll casing. In the range where the angular position ranges from 60 degrees to 180 degrees, the relationship α≦70° is satisfied;
Scroll casing according to claim 6. A scroll casing for a centrifugal compressor,
a diffuser section forming a diffuser flow path of the centrifugal compressor;
a scroll portion forming a scroll flow path of the centrifugal compressor;
The flow path width of the diffuser flow path along the axial direction of the centrifugal compressor is Ta,
a virtual circular arc that touches from a starting end position on the inner circumferential surface of the scroll portion, which is a connection position of the diffuser flow path with the hub-side flow path surface, to a terminal end position, which is an end position on the opposite side of the starting end position on the inner circumferential surface; Define the shortest distance to Tb,
Regarding the angular position around the center of the scroll in the scroll flow path, the confluence position of the start and end of winding of the scroll flow path is set at 60 degrees, and the angle gradually increases from the confluence position toward the downstream side of the scroll flow path. If you define the angular position so that
In the range where the angular position ranges from 180 degrees to 360 degrees, the relationship Tb/Ta≧1.0 is satisfied,
The length along the axial direction of the centrifugal compressor between the terminal position and the downstream end of the shroud side flow path surface of the diffuser flow path at the angular position θ1 is T1,
When the length along the axial direction between the terminal position and the downstream end of the shroud side flow path surface at the position θ2 where the angular position is larger than θ1 is defined as T2,
satisfies the relationship T1<T2 ,
scroll casing. A centrifugal compressor comprising the scroll casing according to any one of claims 1 to 8 .

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